Conduit space recovery system

ABSTRACT

Space in a conduit having at least one cable therein which is surrounded by a duct is recovered by longitudinally cutting the duct and removing the duct from around the cable. The duct may be pulled out of the conduit and past a blade to affect the cutting, or a blade may be pulled through the conduit to cut the duct while still in the conduit.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from the U.S. Provisional PatentApplication Ser. No. 61/562,035 filed Nov. 21, 2011.

TECHNICAL FIELD

This invention relates to conduits which house communications cableswithin innerducts in the conduits. More specifically, this inventionrelates to a system for removing the innerducts from around live cablesso as to recover space in the conduits which can then be used to receiveone or more additional cables.

BACKGROUND ART

It is likely that there are currently millions of miles of conduitsburied under ground, which conduits carry one or more communicationscables. Typically these cables are housed in plastic innerductspositioned in the conduit. The purpose of these innerducts is to protecta cable when an additional cable might be installed in the same conduit.In addition, it is easier to install the additional cables if they tooare in separate innerducts.

There comes a time, however, when the conduit is essentially filled withinnerducts and no more cables can be installed therein. Such a situationis shown in FIG. 1A where a conduit 10 is filled with innerducts 11,each of which are carrying a live or active cable 12. These innerductscannot readily be removed because, to date, the only known way to do sowould be to sever a cable, which cannot be done if it is an activecable. As such, if additional communications cables are needed in thatgeographical area, a new conduit must be buried in the ground which is avery labor intensive, time-consuming, and expensive project.

Thus, the need exists to recover the space in a conduit which is beingtaken up by one or more innerducts so that additional cables can beinstalled in the existing conduit.

DISCLOSURE OF THE INVENTION

It is thus an object of one aspect of the present invention to provide asystem of recovery space in a conduit by cutting and removing from theconduit an innerduct which houses a live cable.

It is an object of another aspect of the present invention to provide asystem, as above, wherein the innerduct is cut while it is being removedfrom the conduit.

It is an object of an additional aspect of the present invention toprovide a system, as above, wherein the innerduct is cut while still inthe conduit and thereafter removed.

These and other objects of the present invention, as well as theadvantages thereof over existing prior art forms, which will becomeapparent from the description to follow, are accomplished by theimprovements hereinafter described and claimed.

In general, in accordance with one aspect of the present invention, amethod of recovering space in a longitudinally extending conduit havingat least one cable surrounded by a longitudinally extending duct in theconduit includes the steps of longitudinally cutting the duct andremoving the duct from around the cable.

In accordance with another aspect of the present invention, a method ofrecovering space in a longitudinally extending conduit having at leastone cable surrounded by a longitudinally extending duct in the conduitincludes the steps of moving the duct out of the conduit and, as theduct is being moved, cutting the duct so that is may be removed fromaround the cable.

Another aspect of the present invention involves a method of recoveringspace in a longitudinally extending conduit having at least one cablesurrounded by a longitudinally extending duct in the conduit whichincludes the steps of accessing the conduit and the duct in a manholeand pulling the duct a short distance into the manhole. The duct is thenengaged and moved toward a blade assembly which cuts the ductlongitudinally into at least two pieces which are then removed fromaround the cable.

One form of apparatus for cutting a duct which surrounds a cable in alongitudinally extending duct includes a drive assembly is adapted toengage the duct and pull the duct out of the conduit. A cutting assemblyis carried by each arm to longitudinally cut the duct. A cuttingassembly is positioned to longitudinally cut the duct as it is beingpulled by the drive assembly.

Preferred exemplary systems for recovering space in a conduit accordingto the concepts of the present invention are shown by way of example inthe accompanying drawings without attempting to show all the variousforms and modifications in which the invention might be embodied, theinvention being measured by the appended claims and not by the detailsof the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic and end view of a conduit which is filled withthree innerducts, each of which is housing a communications cable.

FIG. 1B is a schematic view, like FIG. 1, showing that the innerductshave been slit lengthwise.

FIG. 1C is a schematic view, like FIGS. 1 and 2, showing the space inthe conduit that is recovered after the split innerducts have beenremoved.

FIG. 2 is a somewhat schematic, fragmented, sectional view of a typicalmanhole with a cable extending therethrough.

FIG. 3 is a sectional view taken substantially along line 3-3 of FIGS. 2and showing an end wall of the manhole.

FIG. 4 is a schematic view like FIG. 2 showing a portion of an innerducthaving been removed from the conduit.

FIG. 5 is a schematic top representation of a device positioned in themanhole which cuts and removes the innerduct from the conduit accordingto one aspect of the present invention.

FIG. 6 is a schematic representation similar to FIG. 5 showing somealternative features of the present invention.

FIG. 7 is a somewhat schematic depiction of an alternate system to cutand remove innerduct from the conduit.

FIG. 8 is an end view of the device of FIG. 7.

PREFERRED EMBODIMENTS FOR CARRYING OUT THE INVENTION

A conduit 10 for carrying communications cables 12 typically will extendlongitudinally in the ground for up to thousands of feet. As previouslydescribed, when multiple cables are to be positioned in a conduit, it iseasier to insert them and to keep them from damaging existing cable orbeing twisted with existing cable by inserting them into some kind ofduct, commonly known as an innerduct, such as the plastic tubinginnerduct 11 shown. However, as shown in FIG. 1A, these innerducts 11take up space that could otherwise be used for additional cables 12.

In accordance with the present invention, as shown in FIG. 1B, one ormore of the innerducts 11 may be cut along their length, as at 13, atmultiple locations. Then the pieces of innerduct 11 may be removed fromaround the cables 12 which creates a recovered space 14 in the conduit10 as shown in FIG. 1C. Then it would be preferable to encase the freedcable or cables 12 in a fabric sleeve so that additional cables could beinserted into conduit 10 without encountering the friction caused by anexposed cable and without potentially damaging existing cable. Inaddition, a fabric innerduct M, such as that shown in U.S. Pat. No.6,251,201, and sold under the trademark MAXCELL® by Wesco Distribution,Inc. of Pittsburgh, Pa., could be inserted into space 14 and new cablescould be inserted of inside the compartments of the fabric innerduct.

FIG. 2 schematically depicts a conventional cable service point such asa manhole generally indicated by the numeral 15. Manhole 15, of course,has a normally covered open top 16, a bottom surface 17 on which workersmay stand, and sidewalls 18. When conduits are initially inserted in theground 19, manholes 15 are provided every several hundred feet foraccess to the cables 12 (one shown in FIG. 2 for convenience) whichextend across the manhole 15 from one sidewall 18 to the other sidewall18. The cable 12 shown in FIG. 2 is fragmented to indicate that thecable 12 does not pass through the manhole 15 from one sidewall 18 tothe other. Rather, typically, a coil of cable 12 may be found in amanhole 15. As shown in FIG. 3, the conduit 10 and innerducts 11 (oneshown in FIG. 3 for convenience) are exposed in manhole sidewalls 18.

The operation of the system of the present invention can take place in amanhole 15, and in accordance with an embodiment of the presentinvention, the innerduct 11 to be operated upon can be pulled a shortdistance into the manhole as shown in FIG. 4. Then an assembly,generally shown in FIG. 5, can be used to remove and cut innerduct 11 asnow will be described.

Assembly 20 is shown as having a frame generally indicated by thenumeral 21. Frame 21 includes spaced support arms 22 the edges of whichrest against manhole sidewall 18. Arms 22 are spaced from each otherwith cable 12 being positioned therebetween. Each arm 22 carries a drivedevice generally indicated by the numeral 23. Drive 23 can be as shownin the form of rotating wheels 24 or could be in the form of aconventional tractor drive. In the form shown, wheels 24 first clampdown on opposite sides of the exposed innerduct 11, as is shown in FIG.5, and then wheels 24 may be rotated in opposite directions, as shown bythe arrows in FIG. 5, to pull innerduct 11 out of the conduit 10 andmove it to the left in FIG. 5. Wheels 24 may be hydraulically driven andmay be provided with a knurled surface to assist in the engaging andpulling functions. Since frame 21 is braced against manhole sidewall 18,the force used in the pulling process is borne by sidewall 18.

Each arm 22 of frame 21 also includes a cutting device generallyindicated by the numeral 25. In the embodiment shown in FIG. 5, cuttingdevice 25 is schematically shown to be in the form of a stationary blade26. Opposed blades 26 extend inwardly from each arm 22 a sufficientextent so as to come into contact with innerduct 11 but not so far as totouch and potentially damage active cable 12. Thus, as drive 23 movesinnerduct 11 past cutting device 25, innerduct 11 is longitudinallysevered at two circumferentially spaced locations and the cut pieces 27of innerduct 11 may be removed from around cable. If desired to cutinnerduct 11 in three or more locations, additional cutting devices 25can be provided. Pieces 27 may then be ground up and environmentallyrecycled.

FIG. 6 depicts some alternative features to the embodiment of FIG. 5just discussed. Thus, as shown in FIG. 6, the drive device 23 is shownin the form of conventional tractor devices 28 and the cutting device 25is shown in the form of rotating cutter wheels 29. Cutter wheels 29 canrotate in a clockwise direction against the direction of movement of theinnerduct 11 or, if desired, could rotate in a counterclockwisedirection to actually assist tractor devices 28 in the movement ofinnerduct 11.

FIG. 6 also shows that if desired, a split metal tube 30 can be insertedinto the conduit 10 and around innerduct 11 if guidance of the innerduct11 is required as it is being removed from the conduit 11. Tube 30extends out of the conduit and into manhole 15 and is shown as having aslot 31 at the location of drive devices 23 so that they may engage theinnerduct 11 and other slot 32 at the location of cutting devices 25 tothat they may longitudinally sever the innerduct 11. Moreover, ifnecessary to protect the live cable 12 from damage which might beoccasioned by accidental contact with the cutting devices 25, a splitmetal tube 33 may be inserted a short distance into conduit 10 aroundcable 12. Tube 33 extends into manhole 15 to 50 protect cable 12, ifnecessary.

FIGS. 7 and 8 show an alternative system to accomplish space recovery ina conduit. There, a cutting assembly, generally indicated by the numeral40, includes a body portion generally indicated by the numeral 41. Bodyportion 41 must extend around the cable 12, but because live cablescannot be severed, body portion 41 is split into two sections 41A and41B. Body portion 41 is installed around a cable 12 at a service point,such as the manhole previously described, where the cable 12 is exposed.The innerduct having an edge 42 may then be pulled into the manhole andthe two halves can then be positioned around the cable 12 and can beconnected by any suitable means. For example, each half 41A, 41B may beprovided with a small apertured flange 43 which mate with each other andreceive a fastener.

Cutting assembly 40 includes a plurality of outer guides 44 which arepositioned on the circumferential outside of the innerduct 11 beingworked on. A blade 45 extends from each guide 44 to body portion 41.Blades may be attached to guide 44 and/or body portion 41 in such amanner that they could be readily changed, if necessary. While threeblades 45 are shown, which will longitudinally slit innerduct 11 intothree pieces, as is evident from the previous discussion of FIGS. 5 and6, at least two blades 45 are required. Moreover, more than three blades45 could be utilized if desired. At the outset of the cutting process,blades 45 are positioned adjacent to end 42 of innerduct 11.

Blades 45 longitudinally slit innerduct 11 by causing relative movementbetween cutting assembly 40 and innerduct 11. This can happen by causingcutting assembly 40 to remain stationary and pulling innerduct 11 pastblades 45 (to the left in FIG. 2) in a similar manner as described withrespect to FIGS. 5 and 6. Or cutting assembly 40 can be caused to movethrough the conduit 10. Such can be accomplished by blowing one or morepull tapes into the conduit 10 in a conventional manner. Then thetape(s) can be attached to the cutting assembly 40. To that end, bodysections 41A and 41B may be provided with slots 46 so that the pull tapecan be connected thereto. Then by pulling on the tape, downstream fromthe end 42 of innerduct (at the next adjacent manhole), cutting assembly40 can move, to the right in FIG. 2, through conduit 10 to cut innerduct11. Slots 47 are also provided at the other end of cutting assembly 40so that a tape can be attached thereto to pull cutting assembly 40 inthe reverse direction, if necessary.

When the innerduct 11 has been longitudinally split as shown in FIG. 1B,its pieces may be easily pulled out of conduit 10. If additionalinnerducts 11 are in conduit 10 and if it is desired or necessary toremove them all, the process may be repeated until all innerducts arespliced and removed creating the recovered space 14. As previouslydescribed, the pieces of the innerduct may be ground up andenvironmentally recycled. Once the space of one or more removed ductshas been recovered, the fabric innerduct M such as that shown in U.S.Pat. No. 6,251,201 could be inserted into that space so that one or morenew cables could be inserted into the fabric innerduct.

In view of the foregoing, it should be evident that a conduit spacerecovery system as described herein accomplishes the objects of thepresent invention and otherwise substantially improves the art.

1. A method of recovering space in a longitudinally extending conduithaving at least one cable surrounded by a longitudinally extending ductin the conduit comprising the steps of longitudinally cutting the duct,and removing the duct from around the cable.
 2. The method of claim 1wherein the step of cutting and removing are done generallysimultaneously.
 3. The method of claim 1 wherein the step of cuttingincludes the step of moving the duct past a blade.
 4. The method ofclaim 3 wherein the step of moving includes the step of pulling the ductout of the conduit.
 5. The method of claim 1 wherein the step of cuttingincludes the step of moving a blade through the conduit.
 6. The methodof claim 1 wherein the step of cutting includes the step of cutting theduct of at least two circumferentially spaced locations to form piecesof duct.
 7. The method of claim 1 further comprising the step ofinserting an innerduct in the recovered space.
 8. A method of recoveringspace is a longitudinally extending conduit having at least one cablesurrounded by a longitudinally extending duct in the conduit comprisingthe steps of moving the duct out of the conduit, and as the duct isbeing moved, cutting the duct so that the duct may be removed fromaround the cable.
 9. The method of claim 8 wherein the step of movingincludes the step of grasping the duct with opposed wheels, and rotatingthe wheels to pull the duct out of the conduit.
 10. The method of claim8 wherein the step of moving includes the step of engaging the duct withopposed tractor drives.
 11. The method of claim 8 wherein the step ofcutting includes the step of moving the duct past fixed blades.
 12. Themethod of claim 8 wherein the step of cutting includes the step ofmoving the duct past rotating blades.
 13. The method of claim 8 furthercomprising the step of guiding the duct as the duct is being moved outof the conduit.
 14. The method of claim 8 further comprising the step ofprotecting the cable while cutting the duct.
 15. The method of claim 8further comprising the step of inserting an innerduct in the recoveredspace.
 16. A method of recovering space in a longitudinally extendingconduit having at least one cable surrounded by a longitudinallyextending duct on the conduit comprising the steps of accessing theconduit and duct in a manhole, pulling the duct a short distance intothe manhole, engaging the duct, moving the engaged duct toward a bladeassembly, cutting the duct longitudinally into at least two pieces, andremoving the pieces from around the cable.
 17. Apparatus for cutting aduct which surrounds a cable in a longitudinally extending conduitcomprising a drive assembly adapted to engage the duct and pull the ductout of the conduit, and a cutting assembly positioned to longitudinallycut the duct as it is being pulled by said drive assembly.
 18. Theapparatus of claim 17 further comprising a tube positioned around theduct to guide the duct out of the conduit and toward said cuttingassembly.
 19. The apparatus of claim 17 further comprising a tubepositioned around the cable to protect the cable from said cuttingassembly.
 20. The apparatus of claim 17 wherein said drive assemblyincludes wheels engaging the duct and rotating to move the duct.
 21. Theapparatus according to claim 17 wherein said drive assembly includes atractor drive to move the duct.
 22. The apparatus of claim 17 whereinsaid cutting assembly includes fixed blades.
 23. The apparatus of claim17 wherein said cutting assembly includes rotating blades.
 24. Theapparatus of claim 17 further comprising a frame carrying said drivedevice and said cutting device.
 25. A method of removing alongitudinally tubular member from its position underground comprisingthe steps of longitudinally cutting the tubular member by moving a bladeassembly longitudinally through the tubular member to cut the tubularmember into a plurality of pieces, and removing the pieces fromunderground.